ecl_devices Documentation

ecl_devices

Provides an extensible and standardised framework for input-output devices.

Embedded Control Library

Introduction

    Devices provide a c++ interface (usually on top of a lower level
    api such as posix) for input-output manipulation.

It's pretty hard to find a library that treats devices in anything
but an ad-hoc way. There is no consistent interface. This attempts
to bring that to the subset of devices that control systems use.
It also allows hooking of streams to each and any of the devices.

    Also of interest, there are a few very theoretical approaches 
    to writing c++ devices. The ecl's first version too was along 
    these lines, but ultimately     for control systems, being practical 
    wins over syntactic correctness.

    The devices here are kept as consistent and practical as possible
    without sacrificing speed.

Compiling & Linking

    Include the following at the top of any translation unit which
    requires this library:
#include <ecl/devices.hpp>
// Device Classes
using ecl::OFile;
using ecl::Serial;
using ecl::OConsole; // Also IConsole, EConsole, but dont use directly, use console streams instead.
using ecl::String; // Dont use directly, use StringStream instead.
using ecl::SocketClient; // Simple and does ipv4 only.
using ecl::SocketServer; // Simple and does ipv4 only.

You will also need to link to -lecl_devices.

Device Usage

Open/Close

            All devices have both RAII and non-RAII setup methods. In practice, this means you either bundle all configuration
            into the constructor, or you utilise the open() method to do configuration yourself. Usually RAII is the more ideal
            approach, but sometimes its inconvenient so the latter method is also available. For example, the serial class:
Serial serial_raii("/dev/ttyS0",BaudRate_115200,DataBits_8,StopBits_1,NoParity); // RAII
Serial serial_nonraii;
serial.open("/dev/ttyS0",BaudRate_115200,DataBits_8,StopBits_1,NoParity); // non-RAII

Cleanup is always done in the destructor, though if you need to manually open/close a device frequently, a close() method is also provided.

Read/Write

            Some class are output devices (only write), others are input devices (only read) and some can do both. The read
            and write modes will sometimes be configurable, (e.g. timeout or non-blocking for serial reads), however the
            actual read and write operations will always be the same.
int n;
char buffer[256];
n = source.read(buffer,256);
n = sink.write("dude\n",5);

Exceptions

Concepts

            Essentially, a device class can be written in any way you please.
            However, if you wish to connect it to higher level components, in particular,
            streams, you must ensure you class satisfies certain device concepts. Refer to the
            documentation in ecl_concepts for more information.

Devices

OFile

            - <i>IO</i>: write
            - <i>Seekable</i>: no
            - <i>Sync/Async</i>: synchronous

            This is the logger class. Since its primary purpose is to serve logging, the option to
            make it seekable was dropped to keep it nice and simple.

            @sa @ref ecl::OFile "OFile".

SharedFile

            - <i>Status:</i> DEPRACATED (can resurrect if needed)
            - <i>IO</i>: write
            - <i>Seekable</i>: no
            - <i>Sync/Async</i>: synchronous.

            This is a multithreaded version of the SharedFile class. Multiple instances can open
            the same file (uniquely identified by a string) and each contains its own buffer that is
            utilised between flushing (this protects your output from getting tangled unnecessarily).

            @sa @ref ecl::SharedFile "SharedFile".

Serial

            - <i>IO</i>: read/write
            - <i>Seekable</i>: no
            - <i>Sync/Async</i>: synchronous

            The most important thing to note with the serial class is that it really doesn't implement much of the underlying api.
            Rather it wraps a configuration appropriate for control and keeps it as simple as possible.

            Of the possible read modes, it utilises only a timeout mode and a non-blocking mode. The other modes generally do not work
            very well at the speed that control loops need to run.

            @sa @ref ecl::Serial "Serial", @ref ecl::BaudRate "BaudRate", @ref ecl::DataBits "DataBits", @ref ecl::StopBits "StopBits", @ref ecl::Parity "Parity".

String

            - <i>IO</i>: read/write
            - <i>Seekable</i>: no
            - <i>Sync/Async</i>: synchronous

            This is a virtual device used for storing and converting strings (similar to Converters, but more general).
            It is not intended for direct use, but as a mechanism for the stringstream class
            which functions very similarly to the c++ stringstream classes.

            @sa @ref ecl::String "String".

Sockets

            - <i>IO</i>: read/write
            - <i>Seekable</i>: no
            - <i>Sync/Async</i>: synchronous

            These are a very simple/rough implementation of ipv4. It isn't designed to be an industrial strength tool - just something for simple cross platform connections to enable quick and simple remote debugging program builds (or similar).

            Of the possible read modes, it utilises only a timeout mode and a non-blocking mode. The other modes generally do not work
            very well at the speed that control loops need to run.

            @sa @ref ecl::SocketClient "SocketClient", @ref ecl::SocketServer "SocketServer".

Unit Tests

    - src/test/files.cpp
    - src/test/shared_files.cpp

Examples

    - src/examples/serial_timeout.cpp : shows off the low latency timeout code [posix only].

Utilities

    - ecl_core_apps/src/benchmarks/files.cpp
    - ecl_core_apps/src/demos/socket_client.cpp
    - ecl_core_apps/src/demos/socket_server.cpp
    - ecl_core_apps/src/utils/hex.cpp : simple utility for reading/writing hex across the serial cable.
    - ecl_core_apps/src/utils/serial.cpp : simple serial testing utility.

ChangeLog

    - <b>Apr 11</b> : Overhauled error handling.
    - <b>May 10</b> : Serial win32 implementation.
    - <b>May 10</b> : Cmake win32 framework.
    - <b>Jan 10</b> : A simple ipv4 @ref ecl::SocketServer "socket server".
    - <b>Jan 10</b> : A simple ipv4 @ref ecl::SocketClient "socket client".
    - <b>Dec 09</b> : A virtual @ref ecl::String "string" device.
    - <b>Nov 09</b> : Multi-threaded output to a @ref ecl::SharedFile "shared file" (aka thread-safe ofile).
    - <b>Nov 09</b> : @ref ecl::OConsole "OConsole" : also IConsole and EConsole for standard output handling.
    - <b>Sep 09</b> : Synchronised @ref ecl::OFile "output file" devices (posix).
    - <b>Sep 09</b> : An rs-232 @ref ecl::Serial "serial device" interface (posix).


ecl_devices
Author(s): Daniel Stonier
autogenerated on Thu Jun 6 2019 21:59:01